Conventional woven, knitted or non-woven textiles and fabrics have properties such as water vapour transmissibility, wicking behaviour and thermal insulation characteristics that are reliant upon the fabric construction and remain substantially invariant when changes occur in ambient conditions or in the physical activity of a wearer of a garment made from such textiles. In this specification, the term “textile” is used to mean a flexible material comprising a network of natural or artificial fibres, threads or yarns which has been formed by weaving, knitting, crocheting, or by entanglement (e.g. for non-woven or felted textiles). The term textile is meant to incorporate such terms as fabric, cloth, ticking or the like.
It is known in the prior art to use layers of materials such as porous, hydrophobic membranes (such as porous fluoropolymer membranes) in order to provide so-called breathable water-repellent layers, which are impermeable to liquid water but which may permit the passage of water vapour through the pore structure.
One problem with such hydrophobic membranes is that as the ambient temperature approaches body temperature or increases above body temperature (say 37° C.), the water vapour flow through the membrane may be inadequate for the comfort of a person wearing a garment containing the membrane, particularly when that person is active and generating sweat from their body.
The use of hydrogel particles disposed or dispersed throughout a binder or matrix, where the hydrogel particles are present as a discontinuous dispersed solid phase in a continuous solid matrix, is known in the prior art.
US 2008/0057809 A1 discloses a textile having a smooth surface with one or more regions having a bound coating of hydrogel exhibiting expansion or contraction in response to a change in relative humidity and/or exposure to sweat adjusting insulation performance, air movement and/or liquid management of the textile fabric in response to ambient conditions. The hydrogel is in the form of particles disposed in a binder, the particles having a particle size in the range from 1 to 5000μ. The hydrogel particles may themselves be in the form of an interpenetrating polymer network, for instance of poly(N-isopropylacrylamide) and hydrophilic polyurethane, with these particles held or disposed in a binder, and the binder holding the dispersed particles deposited on a surface of a textile. US 2008/0057809 A1 also discloses responsive yarns and/or fibres having a plurality of gel particles disposed in a binder such as polyurethane, silicone rubber or polyacrylic polymer.
US 2003/0010486 A1 discloses a web of material for a wet suit which has a layer of gel particles (1 to 5000 micrometers in size) embedded in a foam matrix.
The prior art materials may exhibit disadvantages related to low mechanical strength arising from the dispersed hydrogel particles, particularly for thin layers or fibres, and the binder or matrix may need to be hydrophilic, or need to be rendered hydrophilic, in order to allow moisture to pass into the hydrogel particles through the binder or matrix.
It is desirable to provide a textile or membrane which presents a thermally insulating layer, through which air and/or liquid water cannot easily pass at low temperatures, but which also provides a more open structure at higher temperatures so that air and moisture vapour can pass through the textile or membrane allowing a wearer to be cooled by evaporation of sweat from the skin, to improve comfort. It is also desirable that such a membrane or textile should permit water vapour to pass out through it even at low ambient temperatures, but that water vapour permeability should increase at higher temperatures, in order to prevent an active user from generating a layer of undesirable, un-evaporated sweat against the skin of the wearer. It is also desirable that such a coating or membrane should be effective if applied as a thin coating layer, and/or should be strong enough to be self supporting as a membrane. It is also desirable to provide a composite material in the form of a fibre or yarn suitable for use in the manufacture of textiles.